Raidoactive therapeutic seed having selective marker configuration

Abstract

Radioactive therapeutic seeds include a carrier structure bearing a radioactive isotope and a radiopaque marker. According to several embodiments, the seeds include a central plug provided with an axial marker and a relatively transverse bore extending through the marker. A second marker may be positioned in the bore, thereby distinguishing a seed provided with the second marker relative to a seed not provided with the second marker. According to another embodiment, the isotope is deposited on the outer surface of a hollow radiolucent tube. A biologically-compatible, radiolucent, surface-sealing layer seals the external surface of the tube. A radiopaque marker wire of selected length is positioned in the hollow of the tube. Seeds may be distinguished from one another by providing seeds with marker wires of different lengths. According to other embodiments, the seed includes a cylindrical outer member, and an inner member provided within the outer member and having two large diameter portions and a relatively smaller diameter portion therebetween. A marker is disposed within the inner member, and a radioactive isotope is carried on the inner member. The marker may be drilled to a smaller size. Each embodiment permits at least two groups of seeds to be distinguished from one another by the use of differing marker configurations.

What is claimed is:  
     
       1. A radioactive therapeutic seed, comprising: 
       a) a substantially cylindrical outer member;  
       b) a substantially stepped cylindrical inner member provided within said outer member and having a small diameter portion and a first relatively large diameter portion;  
       c) a marker disposed within said inner member and viewable as at least one of a radiographic and a MRI image; and  
       d) a radioactive isotope carried on said small diameter portion.  
     
     
       2. A seed according to  claim 1 , wherein: 
       said isotope is disposed directly on said small diameter portion.  
     
     
       3. A seed according to  claim 1 , further comprising: 
       e) a band disposed about said small diameter portion, said isotope being provided on said band.  
     
     
       4. A seed according to  claim 3 , wherein: 
       said band is substantially radiotranslucent.  
     
     
       5. A seed according to  claim 4 , wherein: 
       said band is made of a resilient material.  
     
     
       6. A seed according to  claim 4 , wherein: 
       said band is made of a deformable material.  
     
     
       7. A seed according to  claim 1 , wherein: 
       said outer member has a first open end and said large diameter portion is in mating engagement with said first open end.  
     
     
       8. A seed according to  claim 5 , wherein: 
       said first large diameter portion is welded to said first open end.  
     
     
       9. A seed according to  claim 8 , wherein: 
       said outer member has a second open end,  
       said inner member has a second large diameter portion with said small diameter portion being located between said first and second large diameter portions, and  
       said second large diameter portion being in mating engagement with said second open end.  
     
     
       10. A seed according to  claim 9 , wherein: 
       said first large diameter portion is welded to said first open end, and  
       said second large diameter portion is welded to said second open end.  
     
     
       11. A seed according to  claim 1 , wherein: 
       said marker is longitudinally disposed within said inner member.  
     
     
       12. A radioactive therapeutic seed, comprising: 
       a) a substantially cylindrical outer member;  
       b) a carrier within said outer member, said carrier including first and second stepped members each having a small diameter medial portion and a relatively large diameter lateral portion, said medial portions being directed toward each other, and each of said first and second members including a longitudinal bore;  
       c) at least one marker in at least one of said longitudinal bores, said at least one marker disposed within said inner member and viewable as at least one of a radiographic and a MRI image; and  
       d) a radioactive isotope carried on said carrier.  
     
     
       13. A seed according to  claim 12 , wherein: 
       said longitudinal bores provide an opening into said medial portions.  
     
     
       14. A seed according to  claim 13 , wherein: 
       only one marker extends within said longitudinal bores of both said first and second stepped members.  
     
     
       15. A seed according to  claim 12 , wherein: 
       said longitudinal bores provide an opening into said lateral portions.  
     
     
       16. A seed according to  claim 15 , wherein: 
       a separate marker is provided in each of said longitudinal bores.  
     
     
       17. A seed according to  claim 12 , further comprising: 
       e) a band disposed about said medial portions of said first and second stepped members, said isotope being provided on said band.  
     
     
       18. A subassembly for a radioactive therapeutic seed, comprising: 
       a) an inner device having first and second large diameter portions and a relatively small diameter portion therebetween; and  
       b) a marker disposed within said inner device and viewable as at least one of a radiographic and a MRI image.  
     
     
       19. A subassembly according to  claim 18 , wherein: 
       said inner device is substantially cylindrical.  
     
     
       20. A subassembly according to  claim 18 , further comprising: 
       c) a radioactive isotope carried on said small diameter portion.  
     
     
       21. A subassembly according to  claim 20 , wherein: 
       said isotope is disposed directly on said small diameter portion.  
     
     
       22. A subassembly according to  claim 20 , further comprising: 
       d) a band disposed about said small diameter portion, said isotope being provided on said band.  
     
     
       23. A method of preparing a radioactive therapeutic seed, comprising: 
       a) providing a subassembly which includes a device having first and second large diameter portions and a relatively small diameter portion therebetween, and a marker disposed substantially within said device and which is viewable as at least one of a radiographic and a MRI image;  
       b) providing a radioisotope about said reduced diameter portion of the device;  
       c) inserting said device into an outer tubular member; and  
       d) sealing said device within said outer tubular member.  
     
     
       24. A method according to  claim 23 , wherein: 
       said providing said subassembly includes providing said device with a longitudinal throughbore, and inserting a marker into said throughbore.  
     
     
       25. A method according to  claim 23 , wherein: 
       said providing said subassembly includes providing a marker and forming a material about said marker to form said device about said marker.  
     
     
       26. A method according to  claim 23 , wherein: 
       said providing a radioisotope includes coating said radioisotope directly on said device.  
     
     
       27. A method according to  claim 23 , wherein: 
       said providing a radioisotope includes placing a band member about said smaller diameter portion, said band member including said radioisotope.  
     
     
       28. A method according to  claim 23 , further comprising: 
       e) altering a size of said marker.  
     
     
       29. A method according to  claim 28 , wherein: 
       said altering includes drilling said marker to a reduced size.  
     
     
       30. A method according to  claim 29 , wherein: 
       said marker includes first and second ends, and said marker is drilled substantially equal amounts at said first and second ends.  
     
     
       31. A method, comprising: 
       a) providing a radioactive therapeutic seed having a marker disposed therein, said marker having a size and viewable as at least one of a radiographic and a MRI image; and  
       b) altering said size of said marker while said marker is in said seed.  
     
     
       32. A method according to  claim 31 , wherein: 
       said altering said size is performed by drilling the marker.  
     
     
       33. A method of providing a seed with an imaging marker, comprising: 
       a) providing a radioactive therapeutic seed having a central solid portion;  
       b) drilling a bore at least partially into said solid portion; and  
       c) inserting a marker viewable as at least one of a radiographic and a MRI image into said drilled bore.